How does Cloud-to-Device / inbound communication work? Is it a polling based strategy or something similar to port forwarding or proxy?
On the guide the inbound communication is described as
Hologram exposes an API and a Dashboard interface to send TCP or UDP messages to any port on your cellular device. This requires that your device runs embedded Linux or otherwise implements a networking stack. > The Hologram Cloud translates the API requests (or Dashboard submissions) into raw TCP/UDP messages and sends them to the desired device.
See the Cloud Messaging API reference for details.
And all the relevant API reference has to say about it is
Send a TCP or UDP message to one or more devices on the Hologram network. See the guide for details.
Looks like we have a circular reference going on and the details are nowhere to be found .
My guess is that it works using one or more servers that are connected to the same network as the devices allowing the server to forward requests to the devices, i.e acting as a proxy.
Could this be clarified (and the circular reference be fixed)?